This research was conducted to understand the influence of foliar applied melatonin (0, 50, 100, 150 and 200 μM) on two Salvia species (Salvia nemorosa L., and Salvia reuterana Boiss) under conditions of water stress. Water stress was applied using a reduced irrigation strategy based on re-watering at 80%, 60% and 40% of the field capacity (FC). Increasing water stress, while significantly enhancing malondialdehyde (MDA), H₂O₂, electrolyte leakage, oxidized glutathione (GSSG), and total glutathione (GT), reduced glutathione (GSH), catalase (CAT), peroxidase (POD), superoxide dismutase (SOD) and glutathione reductase (GR) activities, which led to a marked reduction in fluorescence (Fv/Fm). Foliar application of melatonin alleviated the oxidative stress by increasing GT, CAT, POD, SOD and GR activities and reducing GSSG. In particular, melatonin heightened GSH content as well as the ratio of GSH/GSSG when compared to non-sprayed water stressed plants. Melatonin-treated plants had significantly lower SOD and POD activities than control plants under drought stress, while the CAT activity was enhanced with the foliar treatment. Essential oil yield of both Salvia species increased with the decrease in irrigation from 80% to 60% FC but diminished with the more severe water deficit (40% FC). Essential oil components of Salvia nemorosa were β- caryophyllene, germacrene- B, spathulenol, and cis- β- farnesene, while (E) - β- ocimene, α- gurjnnene, germacrene-D, hexyl acetate and aromadendrene was the major constituents of Salvia reuterana. When plants were subjected to water deficit, melatonin treatment increased the concentration and composition of the essential oil. In particular, melatonin treatments improved the primary oil components in both species when compared to non-melatonin treated plants. In conclusion, reduced irrigation regimes as well as melatonin treatments resulted in a significant improvement of essential oil production and composition in both Salvia species.

Background and aims: In recent years, increasing summer temperatures coupled with reduced and erratic rainfall during the growing season have induced accelerated fruit ripening in several regions, resulting in an undesirable increase in wine alcohol content. This study was designed to evaluate the impact of canopy and water management on grape sugar and flavonoid accumulation, with the goal of reducing wine alcohol content while conserving or enhancing flavonoid concentration.\ud Methods and Results: In 2011 and 2012, two irrigation treatments (I–irrigated and DI–deficit irrigated) and two canopy heights (HC–high canopy and SC–short canopy) were applied in a ‘Merlot’ vineyard. No interactions between treatments were observed, and thus, independent results were obtained; DI berries had significantly higher sugar concentration (+5%) than I in both years and higher wine alcohol content only in 2012. SC berries had lower sugar concentration (-4%) than HC and lower wine alcohol (-8%) only in 2011. Anthocyanins and tannins in berry and wine were increased by water deficit and not affected by severe trimming.\ud Conclusion: DI did not reduce berry sugar concentration and wine alcohol content but did enhance desirable wine attributes. SC reduced berry sugar concentration and alcohol content in wine in one of the two seasons. Water deficit and severe trimming showed independent effects on berry composition.\ud Significance of the Study: Severe canopy reduction performed at early stages of ripening can reduce sugars without affecting anthocyanin accumulation in ‘Merlot’. Conversely, deficit irrigation applied before veraison, despite promoting anthocyanin accumulation, may also increase berry sugar concentration at harvest

Background and Aims Postveraison limitation of canopy photosynthesis delays grape berry ripening and reduces sugar accumulation, thus lowering the alcohol content of the subsequent wines. This study was designed to evaluate whether similar results could be obtained by defoliation apical to the bunch zone using a leaf-plucking machine when berry sugar content was approximately 16–17°Brix. Methods and Results In 2011 and 2012, defoliation treatments were applied postveraison to cv. Sangiovese vines (D) on either side of each row using a mechanical leaf remover, and these D vines were compared to a nondefoliated control (C). The machine removed 35% of the leaves on the vine and created a 50-cm vertical window without leaves above the bunch area, but retained a few leaves at the canopy apex (about 0.50 m²/vine). In both years, leaf removal reduced the rate of berry sugar accumulation and led to a 1.2 lower harvest °Brix and consequently, a lower wine alcohol (−0.6%) content in D relative to that of C vines. In 2012, sugar content of D vines, monitored in a group of vines that was not harvested, had recovered to that of C vines 2 weeks after harvest. The concentration of total phenolic compounds in the grapes, the chemical and chromatic characteristics of the wines and the replenishment of soluble sugars, starch and total nitrogen in the canes and roots were similar in the D and C vines. Conclusion To achieve an effective delay in sugar accumulation in the berries, leaves should be removed at 16–17°Brix, and at least 30–35% of vine leaf area should be removed. Significance of the Study Mechanical removal of leaves postveraison above the bunch zone of Sangiovese can be an easy and economically viable technique for delaying sugar accumulation in the berries and for limiting the alcohol content of wines with no negative impact on desirable composition of either berries or wines.

The effectiveness of a postveraison application of the film-forming antitranspirant Vapor Gard (VG, a.i. di-1-p-menthene) was investigated as a technique to delay grape ripening and reduce sugar accumulation in the berry. The study was carried out over the 2010–2011 seasons in a nonirrigated vineyard of cv. Sangiovese in central Italy. Vapor Gard was applied at 2% concentration to the upper two-thirds of the canopy (most functional leaves) and it significantly lowered leaf assimilation and transpiration rates and increased intrinsic water use efficiency. The F_v/F_m ratio was not modified, emphasizing that photoinhibition did not occur at the photosystem II complex, whereas the reduction of pool size of plastoquinone matched well with reduced CO₂ fixation found in VG-treated vines. In both years VG treatment reduced the pace of sugar accumulation in the berry as compared to control vines, scoring a -1.2 Brix at harvest and wine alcohol content at −1% without compromising the recovery of concentrations of carbohydrates and total nitrogen in canes and roots. Concurrently, organic acids, pH, and phenolic richness of grapes and wines were unaffected, whereas there was a decrease in anthocyanin content in the berry (−19% compared to control vines) and in the wine (−15% compared to control vines). The application of VG at postveraison above the cluster zone is an effective, simple, and viable technique to hinder berry sugaring and obtain less alcoholic wines. To be effective the spraying should be performed at ~14 to 15 Brix, making sure that the lower leaf epidermis is fully wetted by the chemical.